The following definitions are introduced for the purpose of clarity.
AAA, Authentication, Authorization and Accounting. AAA is a common name for both RADIUS and DIAMETER, i.e. solutions providing for customer care, control and billing in a large IP network.
BGP, Border Gateway Protocol. BGP is a inter-domain protocol defined by IETF for sharing routes between ISPs. A route is a collection of knowledge of a path from a source to a destination (host).
cdma2000. Code Division Multiple Access 2000 is the North American version of the 3rd generation mobile cellular technology (IMT-2000) for access speeds up to 2 Mbit/s per Mobile Node. cdma2000 is a trade name for 3G systems based on the cdma2000 radio access standards, as well as name identifying the radio access itself.
DIAMETER. A successor of RADIUS with increased security and scalability features. It is standardized by IETF.
DHCP, Dynamic Host Configuration Protocol. DHCP is an Internet Engineering Task Force (IETF) standard for allocating Internet Protocol addresses to User Systems. User Systems can either be Fixed Hosts or Mobile Systems. The allocation is done each time when the User System is started. The allocation is made by a DHCP server to a DHCP client. The DHCP server is controlled by an Internet Service Provider or an IT-department. The DHCP client is a SW embedded in the User System.
DMZ, De-Militarized Zone is a zone between the Internet Service Provider router and Corporate firewall where access is allowed from both the Internet and the Intranet. Normally a subset of the services available on the Intranet is mirrored on the DMZ.
FA, Foreign Agent. The primary responsibility of an FA is to act as a tunnel agent which establishes a tunnel to a HA on behalf of a mobile node in Mobile IP.
HA, Home Agent. One responsibility of the HA is to act as a tunnel agent which terminates the tunnel, and which encapsulates datagrams to be sent to the Mobile Node in Mobile IP.
IETF, Internet Engineering Task Force. IETF is the standardization organization for the Internet community.
IP, Internet Protocol. IP is a network layer protocol according to the ISO protocol layering. IP is the major end-to-end protocol between Mobile and Fixed End-Systems for Data Communications. It is also used in Radio Datacommunications Systems as an underlying transport technology for Tunneling Protocols.
ISP, Internet Service Provider. The ISP is a notation for the domain providing basic IP configuration services to users, i.e. servers for Domain Name System (DNS) and Dynamic Host Configuration Protocol (DHCP).
LDAP, Lightweight Directory Access Protocol is a slim variant of the X.500 Directory Access Protocol for accessing data storage areas such as user databases.
MANET, Mobile Ad hoc Networks is a common name for a family of protocols that provide multi-hop routing in highly dynamic mobile environments.
MIB, Management Information Base. IETF defines a number of MIBs for allowing management via the SNMP (Simple Network Management Protocol) of network elements. The format of a MIB is standard. The content can either be proprietary or standardized.
MIP, Mobile IP. MIP is a standard being defined by IETF on making IP networks mobility aware, i.e. having knowledge on where a Mobile Node is attached to the network. The standard includes the definition of a Foreign Agent and a Home Agent.
MC, Mobile Client. The MC comprises both the Terminal (TE) and the Mobile Termination (MT).
RADIUS, Remote Authentication Dial-In User Service. RADIUS is the currently, widely deployed AAA protocol. It is a protocol for carrying authentication, authorization, configuration and accounting information between a network access server and an ISP RADIUS server.
RAN, Radio Access Network. RAN is the common acronym used for various types of radio access networks in 3G networks, e.g. cdma2000 and UMTS/WCDMA.
SLA, Service Level Agreement. SLA is the common name for a set of terms agreed with the customer on the quality of service that the ISP shall provide. The SLA can related to availability, latency and throughput of network resources.
UMTS, Universal Mobile Telecommunications System. UMTS is the European version for the 3rd generation mobile cellular technology (IMT-2000) for access speeds up to 2 Mbit/s per Mobile Node. One specie radio technology in UMTS is WCDMA.
VLAN, Virtual Local Area Network is a separation of a physical Local Area Network into a set of logical subnets.
VPN, Virtual Private Network is a secure overlay network on a common public infrastructure that allows a corporation to maintain its own addressing and routing between its sites and to remote users.
WLAN, Wireless Local Area Network. WLAN is a local area solution for radio access mobility with speed up to 11 Mbit/s per Mobile Node.
While Internet technologies largely succeed in overcoming the barriers of distance, time and space, existing technologies have yet to fully accommodate the increasing mobility of people with their computers. In order to eliminate this barrier, this invention introduces modifications to the very base of how packets are routed over the Internet by a mobility routing protocol in the core of a mobile virtual private network together with using mobile IP at its edge.
Similarly, as IP networks has evolved to support external business partners and remote access traffic, the traditional approaches to network security fall short. They do not provide the level of granularity needed to control access to sensitive resources. Here again there is a need to change some of the traditional aspects of internetworking. This invention proposes changes to the perimeter security of a corporate network to include user authentication and workgroup level filtering at the point where a mobile client attaches to the workgroup network.
The introduction of 3G mobile networks is all set to make a huge difference to the international business community. 3G networks will provide sufficient bandwidth to run most of the business computer applications providing a reasonable user experience. However, 3G networks are not based on only one standard, but a set of radio technology standards such as cdma2000, EDGE and WCDMA. In the light of this, a common mobility management framework is required in order to allow mobile users to roam between access networks with little or no manual intervention. IETF has created a standard for this purpose called mobile IP. Mobile IP is different compared to other efforts for doing mobility management in the sense that it is not tied to one specific access technology. In earlier mobile cellular standards, such as GSM, the radio resource and mobility management was integrated vertically into one system. On the other hand, mobile IP is re-using the anchor-based mobility management architecture that has been so successfully exploited in GSM networks. Mobile IP is defining a home agent as the anchor point with which the mobile client always has a relationship, and a foreign agent, which acts as the local tunnel-endpoint at the access network where the mobile client is visiting. Depending on which subnetwork the mobile client is currently visiting its point of attachment may change. At each point of attachment, mobile IP either requires the availability of a standalone foreign agent or the usage of a co-located care-of address in the mobile client itself.
In general, the Internet protocol routes packets from a source to a destination by having routers to forward data packets from incoming network interfaces to outbound network interfaces according to routing tables. The routing tables typically maintain the next-hop (outbound interface) information for each destination IP address. The destination IP address typically carries with it information that specifies the IP client's point of attachment to the network. Correct delivery of packets to a client's point of attachment depends on the network identifier portion contained in the client's IP address, which however has to change at a new point of attachment. To alter the routing of the data packets intended for a mobile client to a new point of attachment can be solved by associating a new IP address with that new point of network attachment. On the other hand, to maintain existing transport protocol layer connections as the mobile client moves, the mobile client's IP address must remain the same.
This mobility addressing dilemma is handled in mobile IP by allowing the mobile client to be associated with two IP addresses: a static, “home” address and a dynamic, “care-of” address that changes at each new point of attachment to the Internet. Only the care-of address changes at each new point of attachment. The home IP address assigned to the mobile client makes it logically appear as if the mobile client is attached to its home network. It is the IP address where the mobile client seems to be reachable for other Internet clients and services.
A mobile agent that is provided in a home network receives traffic directed to the mobile client's home IP address when the mobile client is not attached to its home network. When the mobile client is attached to a foreign network, a home agent routes (tunnels) that traffic to a foreign agent using the mobile client's current care-of address. The care-of address, which identifies the mobile client's current, topological point of attachment to the Internet, is used by the home agent to route packets to the mobile client. If the mobile client is not attached to a foreign network, the home agent simply arranges to have the packet traffic delivered to the mobile client's current point of attachment in the home network. Whenever the mobile client moves its point of attachment, it registers a new care-of address with its home agent.
The further delivery by the home agent to the foreign agent requires that each packet intended for the mobile client be modified/extended so that the care-of address appears as the destination IP address. This modification of the packet is sometimes termed a “redirection.” The home agent redirects packets from the home network to the care-of address by constructing a new IP header that contains the mobile client's care-of address as the packet's destination IP address. This new header “encapsulates” the original data packet causing the mobile client's home address to have no effect on the encapsulated packet's routing until it arrives at the care-of address. This encapsulation is commonly known as “tunneling” in the sense that the data packet burrows or tunnels using the new “routing” header through the Internet, while the encapsulated IP header is completely ignored. When the packet arrives at the foreign agent the new “routing” header is removed and the original packet is sent to the mobile client for properly processing by whatever higher level protocol (layer 4) that logically receives it from the mobile client's IP (layer 3) processing layer.
Foreign agents regularly broadcast agent advertisements that include information about one or more care-of addresses. When a mobile client receives an agent advertisement, it can obtain the IP address of that foreign agent. The mobile client may also broadcast or multicast an advertisement solicitation that will be answered by any foreign agent that receives it. Thus, the agent advertisement procedure allows for the detection of foreign agents, lets the mobile client determine is the network number and status of its link to the Internet, and identifies whether it is at home or on a foreign network. Once a mobile client receives a care-of address, a registration process is used to inform the home agent of the care-of address. The registration allows the home agent to update its routing table to include the mobile's home address, current care-of address, and a registration lifetime.
In contrast to mobile IP, a completely different approach to mobility is emerging for mobile nodes in conference and sensor environments. These mobile users need a way to deliver packets between wireless stations without the use of an infrastructure, i.e. routers. Mobile Ad hoc Networking (MANET) is a name given by IETF to the creation of such dynamic and multi-hop networks. Mobile nodes create own adhoc networks for their communication purposes as needed. Wireless LAN is often cited as the default access technology for this purpose, but also other radio technologies, such as Bluetooth, are showing great promise to be used as an radio access to MANETs. The lightweight implementation of Bluetooth allows very small devices to be part of the adhoc network and opens up for the areas of wearable computing and personal area networking.
MANET solves the problem of mobility by changing the very aspect of routing. Instead of creating tunnels as in mobile IP on top of the existing Internet routing protocols, MANET enhances the routing protocols to be both independent of IP address topology and reactive to route changes. A flat topology allows the mobile nodes to change their point of attachment in relation to each other, while still maintaining their network identity, i.e. IP address. Such propagation of individual routes in an IP network does not scale very well and that is where the second aspect of adhoc networks has its role. Reactive route propagation essentially means that a movement of a mobile node is not propagated per default as a route change to all other nodes in the network. For on-going sessions and to immediate peers, the route update is propagated directly, but for distant nodes that has no on-going communication, the route update is not propagated. A distant node will instead retrieve a route on-demand, when needed. Economical discovery and propagation of such routes is the challenge of MANET. Simple MANET protocols, such as adhoc on-demand distance vector (AODV), use pure broadcast, while advanced MANET protocols, such as topology-based routing based on reverse path forwarding (TBRPF), uses unicast or broadcast depending on the position of the peer in a reverse path tree. In the following, we will use the term mobility routing as a common name for routing protocols developed for mobile adhoc networks.
As it turns out, there are nontrivial issues surrounding the simultaneous use of adhoc networks with Mobile IP. Mobile users would naturally expect that both should be useful together; a foreign agent attached to an adhoc network should provide Internet connectivity to every node in the adhoc network. On the other hand, manipulation of the route table by Mobile IP is not completely consistent with the way ad hoc routing protocols may wish to do route table management, i.e. not all mobile node routes are available for the Mobile IP agent at all times. Furthermore, the rules for Mobile IP need to be adjusted so that the agent advertisements can be delivered to every mobile node in the adhoc network across multiple router-hops. It is the intention of this invention to define a new way of combining mobile IP with mobility routing protocols in the sense that the mobility routing protocol is placed as an overlay rather than an access network to mobile IP.
If Mobile IP and adhoc routing are two sides of the same coin, the third aspect of this invention is often placed in stark opposition to mobility. Security solutions on the Internet, and more specifically the deployment of virtual private networks (VPNs), rely on a set of fixed associations maintained between clients and gateways as well as between gateways themselves. In a site-to-site VPN, a VPN gateway that is placed at the enterprise perimeter typically allows any VPN client with the correct IP address to send traffic from the inside of the intranet cloud out through a VPN tunnel to another intranet cloud. This essentially creates a larger intranet where all sites are open territory. This may sound nice from a mobility perspective, but is hardly encouraging from a corporate security perspective. Statistics tells that four out of five intrusions come from the inside. For this reason end-to-end application layer security are normally added to each client-server and peer-to-peer communication most often leading to a proliferation of pop-up windows on the client for entering user identities and passwords for every server and application that the user wants to access. An administrative nightmare that this invention is eliminating through the use of a regular, yet for the mobile user hidden, authentication. The user authentication combined with per packet filtering or more advanced firewall functionality is performed by a VPN gateway at each site of the VPN in order to provide robust security for the local portion of workgroup networks and their individual server resources.
When it comes to remote access to the VPN, typically three classes of users need connectivity into the enterprise network from the outside:                Anonymous users who normally access via the Internet,        External business partners who access through leased lines, and        Corporate users who need remote access to corporate resources.        
Remote corporate users want to receive the same level and ease of access to corporate resources that they enjoy when they are physically located on the enterprise LAN. For this purpose, the VPN gateway applies strong user authentication and reconfiguration of a VPN client that tries to access the intranet from the outside. When inside, the VPN client can reach any and all resources on the intranet unless an application-based authentication is applied as described above for the site-to-site VPN case.
By contrast, Internet users should be able only to access the publicly available servers (e.g. web, mail and ftp). This is normally done by creating a DMZ (de-militarized zone) separate from the intranet, onto which selected resources are mirrored for accessibility from the Internet.
As for external business partners (i.e. extranets), depending on the business need, access is normally provided to an isolated sub-network or directly to a particular server on the intranet. If a business partner needs to roam into the site, i.e. physically work at the company's premises, a separation of the access and service network within the intranet is required. This is achieved in the following invention through the creation of an additional leg on the VPN gateway in very much the same manner as the DMZ was separated from the intranet for publicly available web resources.
In the following description, the term mobile VPN is used for a VPN in which the users are allowed to move around within the intranet, extranet and Internet without loosing their communication sessions, user privileges or security protections. The term mobile workgroup system will similarly be used to denote a subset of the mobile users and server resources in the mobile VPN that are grouped together based on organizational or security aspects to form a tightly knit community.
The following references are also of general interest for the understanding of the present invention:
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Bellur, Bhargav et al; Topology Broadcast based on Reverse-Path Forwarding (TBRPF); IETF Internet Draft; July 2000
Calhoun, Pat et al; DIAMETER Base Protocol; IETF Internet Draft; September 2000
Calhoun, Pat et al; DIAMETER Mobile IP Extensions; IETF Internet Draft; September 2000
Calhoun, Pat et al; Mobile IP Network Access Identifier Extension for IPv4; IETF RFC2794March 2000
Corson S. et al; Mobile Ad hoc Networking (MANET) Routing Protocol Performance Issues and Evaluation Considerations; IETF RFC2501; January 1999
Droms, R.; Dynamic Host Configuration Protocol; IETF RFC2131; March 1997
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Kent, S. et al; IP Authentication Header; IETF RFC2402; November 1998
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